Design of an LED based lightsource for spectral response measurements on solar cells

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Supervisor:
Dr. Plesz Balázs
Department of Electron Devices

The work of my diploma thesis was focused on reforming the light source of now used, small light-intensity spectral response measurement systems with modern high power light sources. My goal was to present a new solution applicable to a SR measurement device with high power LEDs on PCB and arrangement of a new measurement system. For this purpose the necessary criterion, condition and possible solutions were examined. I created three probe panels with three different wavelength Rebel LEDs. On one board there are 49 lighting diodes, the insertion of these happened with a manual installation device. During the procedure of locking the diodes I soldered the pads and fixed the LEDs with reflow soldering on the panel. The light boards were screwed on heat sink and the optimal temperature of LEDs was assured by applying a fan. I measured the light-intensity maps and the temperature of the completed panels. The comparison of the received results with the results of the simulation showed no significant difference. The preliminary SR measurements with the test panels showed that is worth to realize the system.

The aim was to design a light source for SR-measurements with eight different wavelengths, the controlling and power supply circuit. For practical reasons the eight wavelengths were divided into two boards, each one containing the light sources for four different wavelength and the circuitry for current control. The illumination of each wavelength is provided by 64 LEDs. An additional switching panel allows the computer controlling of the multi-coloured light panel. The light-intensity maps were simulated with a MATLAB program for each wavelength. The PCB was designed with Altium Designer Summer 09 program.

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